[Propagation+Space Weather] The W1AW Weekly Propagation Report - 2019 Aug 30 22:21 UTC

[nw7us@sunspotwatch.com]

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The following is the weekly propagation bulletin from W1AW / ARRL (posting on 20190830 22:21 UTC):

QST de W1AW Propagation Forecast Bulletin 35 ARLP035 >From Tad Cook, K7RA Seattle, WA August 30, 2019 To all radio amateurs

SB PROP ARL ARLP035 ARLP035 Propagation de K7RA

The current stretch of spotless days is now over three weeks, according to http://www.spaceweather.com. The continuing quiet seems eerie. For this past reporting week, Thursday through Wednesday, the average daily solar flux (10.7 GHz radiation recorded in Penticton, British Columbia, which roughly tracks with sunspot activity) was only 66. I couldn't recall when the weekly average reported in this bulletin was last that low, and couldn't find any report during the past year with such low activity.

I did an inspection of the numbers and had to go back to the Fall of 2007 to find average solar flux in that range. In 2007 we reported an average of 66.5 in propagation forecast bulletin number 40:

http://www.arrl.org/w1aw-bulletins-archive/ARLP040/2007

Can anyone else find solar flux that low or lower in past bulletins? We have them online going back to 1995:

http://arrl.org/w1aw-bulletins-archive-propagation

If anyone has copies of propagation bulletins prior to 1995, I would love to see them. I began writing the bulletin in March 1991. Before that, W1HDQ was the author. I recall copying the bulletin as a teenager in 1966 using CW but have not found anyone who knows when the bulletin began. I should have asked W1HDQ before he became a silent key.

Predicted solar flux for the next 45 days is 66 on August 30 through September 6, 67 on September 7-11, 68 on September 12-15, 67 on September 16 through October 8, and 68 again on October 9-12, then 67 on October 13.

Predicted planetary A index is 8, 20, 34, 16 and 8 on August 30 through September 3, 5 on September 4-5, 8 on September 6-7, 5 on September 8-21, then 10, 15 and 8 on September 22-24, 5 on September 25-27, then 35, 18 and 10 on September 28-30, 5 on October 1-2, 10 and 8 on October 3-4, and 5 on October 5-13.

Note that the predicted planetary A index is 34 on September 1, which according to W3LPL and the ARRL Letter is the 160th anniversary of the infamous Carrington Event.

https://en.wikipedia.org/wiki/Solar_storm_of_1859

https://arxiv.org/abs/1908.10326

Http://www.spaceweather.com reported a large recurring coronal hole facing Earth, and they expect the effects to be felt this Sunday, September 1. A planetary A index value of 35 is predicted for the next solar rotation, on September 28.

Geomagnetic activity forecast for the period August 30 to September 26, 2019 from OK1HH.

'Geomagnetic field will be Quiet on: September 10-11, 20-21, (25-26) Quiet to unsettled on: August 30, September 3-5, 7-8, 13, 17, 22, 24 Quiet to active on: August 31, September 6, 9, 12, 14-16, 18-19, 23 Unsettled to active on: September 2 Active to disturbed: September 1

'Solar wind will intensify on August (30)-31, September 1 (-2), (4-6) Parenthesis means lower probability of activity enhancement.'

If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for August 22 through 28, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 65.7, 66.5, 66.3, 66, 65.8, 66.1, and 65.9, with a mean of 66. Estimated planetary A indices were 6, 4, 5, 4, 6, 10, and 5, with a mean of 5.7. Middle latitude A index was 7, 4, 5, 5, 6, 10, and 5, with a mean of 6.

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